﻿<p>An <em>IfcTask</em> is an identifiable unit of work to be carried out in a construction project.</p>
<p>A task is typically used to describe an activity for the construction or installation of products, but is not
limited to these types. For example it might be used to describe design processes, move operations and other
design, construction and operation related activities as well.</p>
<p>
Quantities of resources
 consumed by the task are dealt with by defining the
 <em>IfcElementQuantity</em> for the resource and not at the
 instance of <em>IfcTask</em>.</p>

<blockquote class="history">
HISTORY&nbsp; New entity in IFC1.0. Renamed from <em>IfcWorkTask</em> in IFC2x.
</blockquote>
<blockquote class="change-ifc2x4">
IFC4 CHANGE&nbsp; Attributes <em>TaskTime</em> and <em>PredefinedType</em> added. IfcMove and IfcOrderRequest has been removed in IFC4 and are now represented by <em>IfcTask</em>. IfcRelAssignsTasks relationship has been
 removed as well.
    </blockquote>
    <p class="use-head">Attribute use definition</p>
    <p>
      Each occurrence of <em>IfcTask</em> is given a name that is
      indicative of its content (<em>IfcRoot.Name</em>). A textual
      description of the task may be provided and this may be
      further elaborated by a narrative long description
      (<em>IfcProcess.LongDescription</em>). A work method may be
      declared for the method of work used in carrying out a
      task. A task is identified as being either a milestone task
      or not. A milestone task is defined by the marker
      <em>IsMilestone</em>. and has no duration. A status and
      priority for each task may also be set.
    </p>
    <p class="use-head">Time and duration use definition</p>
    <p>
      Compared to previous IFC releases, basic task time
      information (scheduled start time, scheduled finish
      time, duration) is now directly attached to <em>IfcTask</em>
      through the <em>TaskTime</em> attribute. Regular tasks are
      defined through <em>IfcTaskTime</em>. Recurring tasks are
      defined through <em>IfcTaskTimeRecurring</em>. In case a
      regular task is derived from a recurring task both tasks
      should be linked together through a <em>IfcRelNests</em>
      relationship, where <em>IfcRelNests.IsNestedBy</em> points to
      the recurring task and <em>IfcRelNests.Nests</em> points to
      all regular tasks that have been derived from the recurring
      task.
    </p>
    <p class="use-head">Representation of  other activities</p>
    <p>
      The use definitions for <em>IfcTask</em> have been generalised to
      represent other activities as well, including activities
      that had been defined by own entities in previous IFC
      releases. This includes
    </p>
    <ul>
      <li>Order actions</li>
      <li>Move operations</li>
    </ul>
    <p>
      <em>IfcTask</em> represents an order that might be carried
      out by a Helpdesk acting the role of interface for the
      organization between the facility user and the functional
      requirement of fulfilling their needs. The actual task
      represented by the <em>IfcTask</em> entity is turning a
      request into an order and initiating the action that will
      enable the order to be completed. The
      <em>IfcProjectOrder</em> or one of its subtypes including
      maintenance work order, is related to the <em>IfcTask</em>
      using <em>IfcRelAssignsToControl</em>.
    </p>
    <p>
      <em>IfcTask</em> can also be used to describe an activity
      that moves people, groups within an organization or
      complete organizations together with their associated
      furniture and equipment from one place to another. It thus
      replaces the previous IFC entity IfcMove. The functionality
      is represented in <em>IfcTask</em> as follows:<br>
    </p>
<ul>
      <li>Move from: The place from which actors and their
      associated equipment are moving.<br>
      Use <em>IfcRelAssignsToProcess</em> where
      <em>RelatingProcess</em> points to the task and
      <em>RelatedObjects</em> holds the location(s) from which to
      move.</li>
      <li>Move to: The place to which actors and their
      associated equipment are moving.<br>
      Use <em>IfcRelAssignsToProduct</em> where
      <em>RelatedObjects</em> points to the task(s) and
      <em>RelatingProduct</em> points to the location to which to
      move.</li>
     <li>Punch list: A list of points concerning a move that
      require attention.<br>
      Use <em>LongDescription</em> or else identify sub-tasks to
      track punch list items individually via <em>IfcRelNests</em>.</li>
</ul>